The three jaw chuck was designed to align a part being turned to the centerline of a turning device, commonly a lathe. The three jaws move simultaneously and in unison to maintain a center line through its clamping range. Its development significantly decreased the set-up time for machining.
Frequently, however, and particularly in repair work, the centerline of one or more of the turned areas is not aligned with the center of the segment of the part that is being held by the chuck. Also, due to machine wear or surface irregularities of the part, the centers do not align. When this happens, the conventional three jaw chuck is not useable and a four jaw chuck is usually employed.
In a four jaw chuck, each of the jaws moves independently. The jaws are moved to approximately the dimensions of the part about the centerline, the part is placed in, and each jaw is moved to clamp on the part. A dial indicator is placed in contact with the surface of the segment to be worked on and the chuck is rotated by hand to determine the displacement of the centerline of the segment from the centerline of the chuck. The jaws are then moved independently to align the centerlines, the part re-clamped, and alignment rechecked with the indicator. This may take several iterations and 30 to 40 minutes.
Therefore, there is a need for a jaw having a tooth that is easily radially adjustable such that any chuck, and particularly three jaw chucks, can be used and with much shorter set-up time.